Abstract: Provided are a heating device, a substrate processing apparatus, and a method of manufacturing a semiconductor device. The heating device comprises: a heating element including a mountain part and a valley part that are alternately connected in plurality in a meander shape with both ends being fixed; holding body receiving parts respectively installed at ends of the valley parts and formed as cutout parts having a width larger than a width of the valley part; an insulating body installed at an outer circumference of the heating element; a holding body disposed in the holding body receiving part and fixed to the insulating body; the heating element having a ring shape; the insulating body installed in a manner of surrounding the outer circumference of the heating element; and a fixation part configured to fix the heating element to an inner wall of the insulating body.

Abstract: Provided is a substrate processing apparatus. The substrate processing apparatus comprises a reaction vessel configured to process a substrate, and a heating device. The heating device comprises at least one sidewall insulating part surrounding the reaction vessel, a ceiling insulating part placed on the sidewall insulating part and comprising a plurality of stress relief grooves, and a heating element installed at an inner side of the sidewall insulating part.